While "Jerk" uses glove puppets, the play is absolutely not for children. Photo: Alain Monot

It was the best of times, it was the worst of times — all in one night. Thanks to the Under the Radar festival, you can see avant-garde theater go very right and very wrong in quick succession.

On the very-right side is “Jerk.” Adapted by Dennis Cooper from his novella of the same name and directed by French artist Giséle Vienne, the hourlong piece is as accomplished as it is harrowing.

And while it makes prominent use of glove puppets, it is absolutely not for children. It isn’t even for all adults — as those familiar with Cooper’s interest in transgressive sex and violence will gather.

If you have nerves of steel and an open mind, the show is an intense experience, like a mix of “Henry: Portrait of a Serial Killer” and Gus Van Sant’s more experimental movies.

At least the use of puppets somewhat helps us watch these barbaric acts — all the more nauseating since the story is based on real events from the early ’70s.

The closing scene, in which a broken, possibly medicated David stares vacantly into the void, is as disturbing as the final shot of “Psycho.” An uncompromising exploration of nihilism and penitence, “Jerk” is the closest we may ever come to horror theater.

JERK (four stars). P.S. 122, 150 First Ave.; 212- 352-3101.

Doris Mirescu’s “John Cassavetes’ Husbands,” on the other hand, is a black hole of a completely different kind.

Clunkily incorporating live video — the favorite trick of theatrical snake-oil peddlers — this three-hour “extended meditation” on the largely improvised 1970 movie is vacuously self-indulgent and shockingly inept. Casting men in their 20s as the film’s middle-aged anti-heroes is a falsely daring move, further undermined by the actors’ incompetence.

In a program note, Mirescu states that she follows Cassavetes’ “attack on heartless professionalism.” It’s a neat way to preempt criticism of her show for being amateurish — which it is.

At least the audience saw through this sham: Roughly 80 percent fled at intermission.